In a conveying line of an article in which contents such as food are packed in a package such as a film packaging material and are shipped, it is necessary to inspect a condition of the article to prevent a defected article (for example, the contents caught in a sealed portion of the package, the contents damaged in the package, a foreign matter mixed into the package, and the like) from being shipped.
As an apparatus for inspecting such condition of the article, for example, Patent Literature 1 discloses an optical inspection apparatus including an upstream conveying unit and a downstream conveying unit that convey an article, an illumination unit that emits light to the article from above a gap between the upstream conveying unit and the downstream conveying unit, and an imaging unit that images the article from below the gap.